Method for making composite die



1968 R. B. CUBITT 3,408,436

METHOD FOR MAKING COMPOSITE DIE Filed March 26. 1963 2 Sheets-Sheet 1 I INVENTOR i 5' lo Robert Bruce 60bit! V l6 3 :4 i 24 I8 BY [2 After eys Oct. 29, 1968 R. B. CUBITT METHOD FOR MAKING COMPOSITE DIE Filed March 26, 1963 2 Sheets-Sheet 2 INVENTOR.

Robert Bruce Cub/H Attorneys United States Patent gate-Palmolive Company, New York, N.Y., a corporation of Delaware Filed Mar. 26, 1963, Ser. No. 268,031 4 Claims. Cl. 264-225) This invention relates to a method of making dies for the pressing of soap or like relatively soft material into bars, cakes or any desired compact form, and particularly to dies of this type having a specially formed design bearing section, and to methods and apparatus for making the same.

In its preferred embodiment the invention is concerned with a method of making dies for pressing large numbers of small bars of soap of standard size such as the individual cakes supplied in each room by hotels, motels and the like. These establishments have recently required that a name or some other distinct legend or shape be formed on the soap bar to identify the same and as a form of advertising.

Most larger soap pressing dies are formed with internal stainless steel or hard plastic forming surfaces that are smooth and polished except for any intaglio or relief design that may be cut thereinto, which means that a separate die is needed for each soap surface design. This is commercially practical where hundreds of thousands of large soap bars are pressed from the same die day in and day out, but it is not economical or practical to provide a separate permanently inscribed soap die for I each hotel or like customer who may order only a few thousand bars of soap but once or at irregular intervals.

It has been proposed for taking care of this trade to provide one or more soap contacting surfaces of the die members with removable and replaceable panels bear-. ing the respective designs, but difficulties have been encountered in making these fit with enough accuracy to avoid undesired marking of the soap bar, and besides the processes of making and changing the die panels are slow and expensive in terms of labor.

The present invention provides a solution for this problem by making composite soap die members containing accurately molded panel inserts in a speedy inexpensive manner.

It is therefore the major object of this invention to provide a method of making a novel soap pressing die structure having one or more accurately formed die surface insert sections, and the novel method of speedily and inexpensively making such die structure.

Another object of the invention is to provide a method of making a novel soap pressing die structure wherein part of the internal soap contacting and forming surface of the die is a specially formed plastic panel for providing a desired design on the pressed soap bar.

A further object of this invention is to provide a novel method of making a soap die member having a soap contacting and forming surface wherein an insert panel or the like is formed as by molding or casting into a recess in said surface, said panel having an exposed surface which except fer a design is essentially a continuation of said die pressing surface, and wherein the incorporated panel is removable for molding or casting a substitute panel.

A further object of the invention is to provide a method of making a rigid soap pressing die having a smooth soap contacting surface such as metal formed with a recess, and a design forming insert panel of moldable plastic in said recess.

Another object of the invention is to provide a method of utilizing an apparatus for making a soap die having a molded plastic panel in a recess in its soap contacting and forming surface wherein the die member is clamped over a master design bearing blank that closes the recess during molding.

Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawings wherein:

FIGURE 1 is a top plan view of a metal soap pressing die upper member according to a preferred form of the invention;

FIGURE 2 is a section on line 2-2 of FIGURE 1, showing the soap pressing surface recess for receiving the panel;

FIGURE 3 is a section on line 3-3 of FIGURE 2;

FIGURE 4 is a bottom plan view of the soap die member of FIGURE 1 showing the panel recess;

FIGURE 5 is a section similar to FIGURE 2, but showing the insert panel in the recess;

FIGURE 6 is a bottom plan view of the die member of FIGURE 5 showing the panel surface design;

FIGURE 7 is a generally exploded view partly in section showing the parts in position for carrying out the method of the invention;

FIGURE 8 shows the parts of FIGURE 7 in operative assembly and after the plastic material has been introduced to form the insert; and

FIGURE 9 is a top plan view of the jig base showing the master panel recess.

Referring to FIGURES l-6, the soap die assemblies comprise a die box 10 and associated upper and lower die members 11 and 12, which are relatively separable vertically for the introduction of a body of soap into the cavity 13 therebetween to pressed and compacted into the shape and size of the cavity.

Preferably the die box and die member arrangements are the same as disclosed in United States Letters Patent to Sweet et al. No. 2,965,946, issued Dec. 27, 1960, to which reference is made for further detail.

Lower die member 12 has recessed therein a smooth soap contacting surface 14, and upper die member 11 has recessed therein a smooth recessed soap contacting surface 15.

In the illustrated embodiment, die members 11 and 12 may be hard wear resistant steel blocks usually of stain less steel, and the recessed forming surfaces 14 and 15 are smooth without abrupt corners. The size and shape of cavity 13 are the size and shape of the desired soap bar. The upper die member 11 has a continuous sharp edge 16 around its lower circumference surrounding recess 15, and lower die member 12 has a similar continuous sharp edge 17 around its upper circumference surrounding recess 14.

Any conventional arrangements may be used for relative movement of the die members 11 and 12 and introduction of the body of soap therein, such as the arrangements disclosed in said Sweet et al. patent.

As shown in FIGURES 2-4 the metal die member 11 has surface 15 recessed to form a panel mounting recess 18. This recess is generally rectangular with rounded circumferential corners and having a flat bottom face 19 parallel to the medial portion of die surface 15. The sides 21 and 22 of recess 18 are preferably flat and intersect face 19 at right angles.

Completely filling recess 18 is a panel 23 of relatively hard plastic material (FIGURES 5 and 6) which has an exposed smooth fiat surface 24 at the same level as, and substantially a continuation of, die surface 15.

Integrally formed on panel surface 24 is a design 25 shown here in relief to project within cavity 13, and adapted to impress an intaglio design into the compacted soap bar. Alternatively of course the design 25 could be intaglio, or even a combination of intaglio and relief,

with corresponding formation of the compacted soap bar surface.

The panel 23 is secured tightly in place, either by its mode of assembly as will appear, or by separate locking elements as also will appear, or a combination of both.

Should a different design than that at 25 be desired for the soap bar, it is necessary only to displace panel 23 out of recess 18 and replace it with another panel that is identical, except for surface design, and secured sufficiently tightly in place to stay there during die forming of the soap bar.

A preferred method of forming a panel 23 in place on the metal die member will now be described.

The metal die member 11 is formed with three bores 26 leading from the top to open into recess 18, as shown in FIGURE 2.

Referring now to FIGURES 7-9, the die member of FIGURE 2 is placed in a jig comprising a rigid supporting base 27 formed with a central opening 28 surrounded by an annular recessed shoulder 29. Stepped at a higher level than the horizontal planar bottom of shoulder 29 is a further annular flat horizontal shoulder 31 having a planar bottom parallel to that of shoulder 29.

Seated on shoulder 29 is a master blank 32 of hard non-deformable plastic which circumferentially fills the shouldered recess at 29 and projects above it. The flat upper horizontal surface 33 of blank 32 is formed at 34 in reverse intaglio with the design eventually desired to be formed on the panel insert 23.

Die member 11, which circumferentially fills shouldered recess 31, is mounted over the blank 32 with the die surface engaging the upper side of blank 32 and the die is held tightly thereby posts 35 upstanding from holes 36 in the base 27, clamps 37 extending over its upper end, and nuts 38 tightening down on the clamps on the threaded upper ends of posts 35. Thus blank 32 is clamped between the die 11 and base 27.

The entire upper surface of blank 32 is coated with a parting compound, to prevent it sticking to die surface 15 or the molded insert panel to be described.

With the parts so clamped as in FIGURE 8, it will be noted that the rim of the upper flat surface 33 of the blank 32 smoothly and tightly contacts the upper die member surface 15 all around the cavity 18.

Now a suitable moldable material is poured or injected through the central bore 26 until cavity 18 is at least entirely filled and preferably until the material rises to a certain level in all three bores 26. As the fluent material enters central bore 26, air from cavity 18 escapes through the two outer bores 26. This material of course fills the design inscription 34 on blank surface 33. As will appear, this material is preferably a synthetic resin or non-metallic plastic that will set, cure or otherwise harden satisfactorily in the cavity 18.

After the material has hardened within cavity 18 in the jig of FIGURE 8, the nuts 38 and clamps 37 are removed and composite die member 11 simply removed from the jig.

As shown in FIGURE 6, the insert 23 provided by the material is now in place with the design projecting into recess 15, and the die member is ready for use in soap pressing apparatus as in FIGURE 5. Also as shown in FIGURE 5, the anchoring of panel 23 in place may be assured by providing in one or more outer bores 26 suitable fasteners such as screws 39 that have their threaded ends 41 embedded in the plastic material in the lower part of the bore and their enlarged heads 42 seated in countersinks 43 at the upper ends of the bores.

As above pointed out the die member 11 is usually hard metal or plastic resistant to corrosion by acids in the soaps and by moisture. The illustrated die member 11 is one such as heretofore used for replaceable panels inserted into recess 18.

The master blank 32 can be an inscribed plate of any suitable material, and I have found it very satisfactory to use a hard tough machineable plastic such as the polymerized methyl methacrylate resin known as Lucite, which is resistant to heat, water and the soap components and may be easily cleanly molded or machined to provide the desired design. v

A suitable parting compound such as a silicone wax mold release is coated over surface 33, dried and polished. Care is taken not to fill the design inscription. This plate must be such as not to deform when the resin curing requires heat.

This parting compound is also spread over the entire surface of recess 18 and the interior of bores 26, so that when it is desired to replace insert panel 23 by one having a different inscription the entire hardened plastic body may be knocked as a unit out of die 11.

The material of panel 23 must be one that is capable of being reduced to fluent condition for pouring or injecting into bore 26 and occupying the cavity including the design spaces on plate 32, and then curing in situ with substantially no shrinkage to preserve surface continuity with the die.

Preferably the panel material is a thermo setting material that exhibits the following properties, although thermoplastic materials may also be used. It must have low viscosity during pouring to allow the escape of air bubbles. It must have minimum shrinkage during curing or otherwise hardening, preferably a maximum of 1 to 2 percent and certainly well under 5 percent. It must not expand appreciably during hardening, to avoid cracking the die member or undesired distortion. The heat required for hardening should be well below the heat distortion temperature of the die member or plate 32. In fact it is preferable to provide a resin which will harden within a reasonable time at room temperature.

The preferred panel material is a thermo setting resin such as one of the epoxy resins. One of these epoxy resins found quite satisfactory is that known as Shell Epon 815, and its viscosity is suitably adjusted by introduction of a diluent such as a suitable glycerol based resin. While this resin will attain a suitable hardened condition at room temperature. I have been able to accelerate hardening somewhat by overnight storage in a F. oven. It must be appreciated that higher temperatures of hardening may introduce unwanted stresses due to differences in thermal expansion of the die member and the insert 23.

The fasteners 39 which are used in each of bores 24 and 25 are inserted while the resin is still plastic, and when the resin hardens the assembly is locked together permanently.

The foregonig provides an improved method of incorporating insert panels in soap die members which is not only speedy and inexpensive but results in a superior die member wherein the cast insert surface 24 is a substantially smooth continuation of die surface 25. This insert may be speedily and efficiently replaced by another simply by knocking out the hardened insert panel and incorporating a new one by the method described above.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics therefor. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. A method of producing a composite die part having a design panel insert in a recess in the forming surface of a metal die member and being adapted for the pressing of soap or like relatively soft material into a desired solid compact form which comprises the steps of mounting said die member having a plurality of bores leading from the top of said member to said recess in a fixture wherein said recess is closed by a rigid blank that has its inner face extending across said recess substantially continuous with said die forming surface of the die member and formed with the desired design in reverse facing into said recess, introducing a fluent moldable synthetic resin plastic material through a bore in said die member to at least fill said closed recess, allowing said material to harden in said recess and removing the completed composite die part having the molded panel insert fixedly incorporated therein from said fixture, said insert surface being a substantial continuation of said die member forming surface.

2. A method of producing a composite die part having a design bearing plastic panel insert in a recess in the forming surface of a rigid metal die member and being adapted for the pressing of soap or like relatively soft material into a desired solid compact form which comprises the steps of mounting said die member having a plurality of bores leading from the top of said member to said recess in a fixture wherein said recess is closed by a relatively rigid blank of non-metallic plastic that is resistant to deformation when heated and has its inner face extending across said recess substantially continuous with said die forming surface of said die member and formed with the desired design in reverse facing into said recess, introducing thermosetting synthetic resin material through a bore in said die member to at least fill said recess, allowing said material to harden in said recess and separating the completed composite die part having the molded panel insert fixedly incorporated therein from said fixture and said blank, said insert surface being a substantially smooth continuation of the die member forming surface.

3. A method in accordance with claim 2 wherein said die member is provided with a parting compound between coextensive contacting surfaces of said die member and said plastic blank.

3 4. A method of producing a composite die part having a design bearing plastic panel insert in a recess in the forming surface of a rigid die member and being adapted for the pressing of soap or like relatively soft material into a desired solid compact form which comprises the steps of mounting said die member having a plurality of bores leading from the top of said member to said recess in a fixture wherein said recess is closed by a rigid blank that has its inner face extending across said recess substantially continuous with said die surface and formed with the desired design in reverse facing into said recess, pouring fluent moldable synthetic resin plastic material through a bore in said die member to at least fill said recess, introducing a fastener into one of said bores to be partially embedded in said material and interlocked with said die member, allowing said material to harden and separating the completed composite die part having the locked molded panel insert fixedly incorporated therein from said fixture and said blank, said insert surface being a substantially smooth continuation of the die member forming surface.

References Cited UNITED STATES PATENTS 3,100,318 8/1963 Knox 18-44 3,114,174 12/ 1963 Kunetka 18-44 2,677,151 5/1954 Jennings 264-330 2,709,278 5/ 1955 Greer 264-330 3,121,258 2/ 1964 Lagler 18-42 3,134,143 5/1964 Ludewig et al 18-42 2,860,947 11/1958 Kalet 264-338 X 2,965,946 12/ 1960 Sweet et al 264-337 X 3,054,145 9/ 1962 Helpa 264-242 X 3,124,092 3/1964 Raynes 264-337 X 2,679,663 6/ 1954 Schwemler et al 18-44 X ROBERT F. WHITE, Primary Examiner. T. J. CARVIS, F. MARLOWE, Assistant Examiners. 

1. A METHOD OF PRODUCING A COMPOSITE DIE PART HAVING A DESIGN PANEL INSERT IN A RECESS IN THE FORMING SURFACE OF A METAL DIE MEMBER AND BEING ADAPTED FOR THE PRESSING OF SOAP OR LIKE RELATIVELY SOFT MATERIAL INTO A DESIRED SOLID COMPACT FORM WHICH COMPRISES THE STEPS OF MOUNTING SAID DIE MEMBER HAVING A PLURALITY OF BORES LEADING FROM THE TOP OF SAID MEMBER TO SAID RECESS IN A FIXTURE WHEREIN SAID RECESS IS CLOSED BY A RIGID BLANK THAT HAS ITS INNER FACE EXTENDING ACROSS SAID RECESS SUBSTANTIALLY CONTINUOUS WITH SAID DIE FORMING SURFACE OF THE DIE MEMBER AND FORMED WITH THE DESIRED DESIGN IN REVERSE FACING INTO SAID RECESS, INTRODUCING A FLUENT MOLDABLE SYNTHETIC RESIN PLASTIC MATERIAL THROUGH A BORE IN SAID DIE MEMBER TO AT LEAST FILL SAID CLOSED RECESS, ALLOWING SAID MATERIAL TO HARDEN IN SAID RECESS AND REMOVING THE COMPLEXED COMPOSITE DIE PART HAVING THE MOLDED PANEL INSERT FIXEDLY INCORPORATED THEREIN FROM SAID FIXTURE, SAID INSERT SURFACE BEING A SUBSTANTIAL CONTINUATION OF SAID DIE MEMBER FORMING SURFACE. 